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Maintenance Description
 Issue 3 June 2000
9-23
Tests 
9
Transmission Tests 
9
Technicians can use the DDM-2000 FiberReach Multiplexer internal testing 
capabilities for installation and manual troubleshooting. DS1 and DS3 test signal 
generators and detectors are integrated in the system, eliminating the need for 
external test equipment to do transmission testing. 
The DDM-2000 FiberReach Multiplexer lets technicians test specific signals and 
system components. For example, technicians can manually enable the integrated 
test signal generators and detectors for a  DS1/DS3 low-speed interface. Signal 
tests can be run selectively in the multiplex or demultiplex direction.  Refer to the  
test-trmsn
-
t1
 commands in Chapter 11, "Commands and Reports." 
Beginning with FiberReach Release 3.1, the 
test-trmsn
-
t3
 command is 
allowed ONLY if the shelf is equipped with 28-type OLIUs in Main and DS3 circuit 
packs in the Function Units slots. Beginning with FiberReach Release 4.0, the 
test-trmsn
-
t3
 command is also allowed if the shelf is equipped with 29-type 
OLIUs in Main and DS3 circuit packs in the Function Units slots. Refer to the  
test-trmsn
-
t3 
commands in Chapter 11, "Commands and Reports,"  for details.
Operations Interface Tests 
9
The DDM-2000 FiberReach Multiplexer provides tests for LED indicators, office 
alarms, and the system controller. Refer to the 
test-led
, 
test-alm
, and 
test-sysctl
 commands in Chapter 11, "Commands and Reports." 
Performance Monitoring 
9
The DDM-2000 FiberReach Multiplexer uses performance monitoring (PM) to 
support proactive maintenance of the network and tariffed service performance 
verification. Proactive maintenance refers to the process of detecting degrading 
conditions not severe enough to initiate protection switching or alarming, but 
indicative of an impending hard or soft failure.  Hard and soft failures result in 
reactive maintenance.
Proactive maintenance consists of monitoring performance parameters 
associated with the SONET sections, lines, and paths within the SONET network.  
Table 9-1 lists the SONET performance parameters monitored by DDM-2000 
systems. These parameters are thresholded to indicate degraded performance. 
When a performance-monitoring threshold is crossed, it is reported to the OS as a 
threshold crossing alert (TCA).  With TL1/X.25, all threshold crossings associated